By default the Kindle is in in debug mode. I’m running Mac OS X Lion and I wanted to get adb to recognize the Amazon Kindle. I’ve added the following to ~/.android/adb_usb.ini
# run this command to add 0x1949 to the adb_usb.ini file
$ echo 0x1949 >> ~/.android/adb_usb.ini
You’ll need to kill adb if it’s running and restart it.
Also you might as well reboot your kindle and plug in the usb cable. After that you should see the kindle when running adb devices
$ adb devices
This should make the Kindle much more reliable with adb, before this change adb would recognize the Kindle about 50% of the time.